Infants, especially those under the age of 6 months, are unable or have difficulty in sitting unassisted, whether in an upright or reclined position. Alternatively, if they cannot sit by themselves, they can either be held or lie on a horizontal surface such as a blanket on a floor, or can be placed in a seat of some sort. Among the advantages of using a seat are comfort and allowing a child to look around. Such a seat would need to provide substantial support for an infant over most of the length of the body -- ideally from the knees up. Additionally, some sort of means for precluding sideways movement of an infant is desirable.
It has been usual in the past to use small baskets or the like to transport and generally retain infants. Some of these baskets are arranged so as to prop up the infant when stationary, such that the infant is in an inclined seating position rather than lying down, and can therefore look around.
Modern types of infant seats and carriers are available that more closely resemble a seat and retain the infant in a shell usually having a bottom, a back and sides and also having some sort of leg apparatus for positioning the seat to a desired position or angle, or laying the seat back to a reclined position. Such a seat could therefore be used for having the infant sit and play, or for sleeping, or for generally carrying the infant around.
Typically, infant carrying seats are used to receive and retain an infant. However, the infant must be removed from the seat in order to change the infant's diaper or to just generally clean the infant in the lower torso region, or more specifically the anal and genital regions. Such necessity is often inconvenient just because of having to move the infant to a change table, change pad, or the like. More importantly, there is not always a place available to change an infant if the infant is not at home. It would be much more convenient if an infant could be changed without being moved from the infant seat.
Another problem that is encountered is that an infant is often too young to hold its legs up so as to allow relatively unobstructed access to the anal and genital areas for cleaning. Even with using change tables, or other horizontal surfaces, there is no means for keeping the infant's legs from obstucting the anal and genital areas. Thus, it is necessary for the person changing the diaper or cleaning the infant to keep the legs up with one hand while cleaning or diapering with the other hand. Furthermore, infants typically tend to roll to one side or another or from side to side while being changed or cleaned, which makes the whole process much more difficult. Additionally, if a raised change table is being used then there is the possibility that the infant may indeed roll off the side of the change table.